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  <p class="align-right"><strong>built-in predicate</strong></p>
<section id="threaded-1">
<span id="predicates-threaded-1"></span><span id="index-0"></span><h1><code class="docutils literal notranslate"><span class="pre">threaded/1</span></code><a class="headerlink" href="#threaded-1" title="Link to this heading"></a></h1>
<section id="description">
<h2>Description<a class="headerlink" href="#description" title="Link to this heading"></a></h2>
<div class="highlight-logtalk notranslate"><div class="highlight"><pre><span></span><span class="k">threaded</span>(<span class="nv">Conjunction</span>)
<span class="k">threaded</span>(<span class="nv">Disjunction</span>)
</pre></div>
</div>
<p>Proves each goal in a conjunction or a disjunction of goals in its own
thread. This meta-predicate is deterministic and opaque to cuts. The
predicate argument is <strong>not</strong> flattened.</p>
<p>When the argument is a conjunction of goals, a call to this predicate
blocks until either all goals succeed, one of the goals fail, or one of
the goals generate an exception; the failure of one of the goals or an
exception on the execution of one of the goals results in the
termination of the remaining threads. The predicate call is true <em>iff</em>
all goals are true. The predicate call fails if all goals fail. When
one of the goals throws an exception, the predicate call re-throws that
exception.</p>
<p>When the argument is a disjunction of goals, a call to this predicate
blocks until either one of the goals succeeds or all the goals fail or
throw exceptions; the success of one of the goals results in the
termination of the remaining threads. The predicate call is true <em>iff</em>
one of the goals is true. The predicate call fails if all goals fails.
When no goal succeeds and one of the goals throws an exception, the
predicate call re-throws that exception.</p>
<p>When the predicate argument is neither a conjunction nor a disjunction
of goals, no threads are used. In this case, the predicate call is
equivalent to a <code class="docutils literal notranslate"><span class="pre">once/1</span></code> predicate call.</p>
<p>A dedicated message queue is used per call of this predicate to collect
the individual goal results.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>This predicate requires a <a class="reference internal" href="../../glossary.html#term-backend-Prolog-compiler"><span class="xref std std-term">backend Prolog compiler</span></a> providing
compatible multi-threading primitives. The value of the read-only
<a class="reference internal" href="../../userman/programming.html#flag-threads"><span class="std std-ref">threads</span></a> flag is set to <code class="docutils literal notranslate"><span class="pre">supported</span></code> when that
is the case.</p>
</div>
</section>
<section id="meta-predicate-template">
<h2>Meta-predicate template<a class="headerlink" href="#meta-predicate-template" title="Link to this heading"></a></h2>
<div class="highlight-logtalk notranslate"><div class="highlight"><pre><span></span><span class="k">threaded</span>(<span class="m">0</span>)
</pre></div>
</div>
</section>
<section id="modes-and-number-of-proofs">
<h2>Modes and number of proofs<a class="headerlink" href="#modes-and-number-of-proofs" title="Link to this heading"></a></h2>
<div class="highlight-logtalk notranslate"><div class="highlight"><pre><span></span><span class="k">threaded</span>(<span class="o">+</span>callable) <span class="o">-</span> zero_or_one
</pre></div>
</div>
</section>
<section id="errors">
<h2>Errors<a class="headerlink" href="#errors" title="Link to this heading"></a></h2>
<div class="line-block">
<div class="line"><code class="docutils literal notranslate"><span class="pre">Goals</span></code> is a variable:</div>
<div class="line-block">
<div class="line"><code class="docutils literal notranslate"><span class="pre">instantiation_error</span></code></div>
</div>
<div class="line">A goal in <code class="docutils literal notranslate"><span class="pre">Goals</span></code> is a variable:</div>
<div class="line-block">
<div class="line"><code class="docutils literal notranslate"><span class="pre">instantiation_error</span></code></div>
</div>
<div class="line"><code class="docutils literal notranslate"><span class="pre">Goals</span></code> is neither a variable nor a callable term:</div>
<div class="line-block">
<div class="line"><code class="docutils literal notranslate"><span class="pre">type_error(callable,</span> <span class="pre">Goals)</span></code></div>
</div>
<div class="line">A goal <code class="docutils literal notranslate"><span class="pre">Goal</span></code> in <code class="docutils literal notranslate"><span class="pre">Goals</span></code> is neither a variable nor a callable term:</div>
<div class="line-block">
<div class="line"><code class="docutils literal notranslate"><span class="pre">type_error(callable,</span> <span class="pre">Goal)</span></code></div>
</div>
</div>
</section>
<section id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Link to this heading"></a></h2>
<div class="line-block">
<div class="line">Prove a conjunction of goals, each one in its own thread:</div>
<div class="line-block">
<div class="line"><code class="docutils literal notranslate"><span class="pre">threaded((Goal,</span> <span class="pre">Goals))</span></code></div>
</div>
<div class="line">Prove a disjunction of goals, each one in its own thread:</div>
<div class="line-block">
<div class="line"><code class="docutils literal notranslate"><span class="pre">threaded((Goal;</span> <span class="pre">Goals))</span></code></div>
</div>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="threaded_call_1_2.html#predicates-threaded-call-1-2"><span class="std std-ref">threaded_call/1-2</span></a>,
<a class="reference internal" href="threaded_once_1_2.html#predicates-threaded-once-1-2"><span class="std std-ref">threaded_once/1-2</span></a>,
<a class="reference internal" href="threaded_ignore_1.html#predicates-threaded-ignore-1"><span class="std std-ref">threaded_ignore/1</span></a>,
<a class="reference internal" href="../directives/synchronized_1.html#directives-synchronized-1"><span class="std std-ref">synchronized/1</span></a></p>
</div>
</section>
</section>


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